As a method used for detection of a line of sight, for example, there is a “method using a corneal reflex technique (a pupil corneal reflex technique) using a corneal reflection image (also referred to as a Purkinje image′) formed such that light from a light source such as an infrared light emitting diode (IR LED) is reflected by a cornea” or the like.
Here, there may be an error between a position or the like at which a user is estimated to be staring from a detection result of the line of sight obtained by using the above-described technique and a position at which the user is actually staring or the like. For this reason, the detection result of the line of sight detected using the above-described technique is calibrated to reduce the error, and the position at which the user is staring or the like is estimated using the calibrated detection result of the line of sight.
Under such circumstances, a technique related to the calibration of the line of sight has been developed. As a technique related to the calibration of the line of sight, for example, a technique described in Patent Literature 1 is known.